Matplotlib is the most widely used if not the most popular data visualizing library in Python. It was created by John Hunter(1968–2012). He was a neurobiologist and was part of a research team that was analyzing electrocorticography(ECOG) signals.
The Team was using proprietary software for the analysis, however, they only had one license, and so they were taking turns in using it. So in order to overcome this limitation, John set out to replace this proprietary software with a MATLAB based version that could be utilized by him and his Teammates and that could be extended by multiple investigators.
As a result, matplotlib was originally developed as an ECOG visualization tool. And just like MATLAB, matplotlib was equipped with a scripting interface for quick and easy generation of graphics, represented by pyplot.